US 2005/0049761 (JP 2004-168148A) discloses a vehicle control system that is capable of suppressing the vibrations of a vehicle body. The vehicle control system corrects an input instruction so as to suppress the vibrations of the vehicle by a motion model. The motion model is formed by a dynamic model of the vibrations of tires of the vehicle, the vehicle body unsprung vibrations in suspensions, and the vehicle body sprung vibration which are received by the vehicle body per se, which occurs according to an input instruction corresponding to at least one of accelerator operation, steering operation, and brake operation which are instructed by a driver.
The above vehicle control system uses a vehicle vibration model including a vehicle body sprung vibration model, a suspension vibration model and a tire model. The vehicle body vibrations make passengers most uncomfortable, and change the ground loads (ground pressures) of the respective wheels, thereby adversely affecting the basic performance of the vehicle such as traveling, curving or stopping. Accordingly, the vehicle control system mainly conducts the control for suppressing the vehicle body vibration.
For example, in the case of conducting the rapid accelerator operation, the behavior of the vehicle body above springs which is caused by a driving torque is calculated by the vehicle vibration model and the drive torque is so corrected as to reduce a pitch rate and a vertical velocity corresponding to the vehicle body behavior above springs. When the corrected drive torque is a negative value, because the control cannot be realized by the drive system, a target braking force for compensating the shortfall is calculated to execute the control in the braking system together.
However, because the vehicle body is mounted on a chassis frame, and the chassis frame is coupled with the tires through the suspensions, the chassis vibrations and the tire vibrations adversely affect the vibrations. Also, because the vibrations occur in the chassis or the tires to change the ground load of the tires, the travel stability of the vehicle may be deteriorated. For this reason, more than just suppressing of the vehicle body vibrations is needed. It is preferred to suppress the vibrations that occur at the respective portions of the vehicle.